Using IR modules from VCRs

1) Intro

Some time ago, I came across the
Lirc (Linux Infrared Remote Control)
website and decided to build a serial port IR receiver. They had a
list of suggested IR receiver modules, but I was unable to buy one, so
I had to think of using something else.

A IR Receiver module is usually a photodiode and a 38khz detector.
Most of them have 3 pins. VCC, GND, an output pin. If a 38khz carrier
is detected, the output pin will become active. Some modules are active
low, and others are active high. It is sometimes required to use an
inverter(eg: 7404) to get the correct signal.

At first I thought to build a 38khz detector and to use a photodiode
for receiving IR, but I soon realized that this would be too much trouble.
Instead, I decided to use the IR module from one of my old VHS I had lying around.

2) Finding the module inside the VCR

This should be pretty easy. Just remove the plastic cover from
the front panel, and you will probably see a small metal cage
somewhere, as shown in the picture to the left.

3) Figuring out the pinout

There are 2 types of modules used in VCRs:

Self-contained modules

Built on board modules

1. Self-contained modules

Self contained modules are usually come with their metal cage soldered
to the PCB, with 3 wires or pins coming out. Here are pictures of such modules:
The pinout is not usually too difficult to guess. If you're lucky, it will be
printed on the pcb like this:
Otherwise, you can find the pinout by trial and error. Simply connect the ground,
vcc. Connect the output pin to a led using a high resistor value like 1k. Also,
limit the current in the VCC line if possible(using a resistor or a good power supply).

To test your pinout, aim a remote control to your module and press a button. The led will blink
if you have the right pinout.

2. Built on board modules

Built on board modules have their metal cage soldered to the PCB, and a bunch of
component (sensor, chips, resistor, caps...) directly soldered to the PCB. If you have
this type of module, I recommend that you cut the PCB around it using a dremel or something.

Next, look at the board layout. Usually, this area is insulated with a ground plane. You will
probably see 3 traces going inside the module like this:
One of them is VCC, another GND, and the last
one is the output. You can easily guess which one is the ground and vcc. Just follow them on the
PCB, and it will eventually connect to other chips. You can look theese chips datasheet to learn their
pinout. If the trace connects to a VCC or GND pin, you got it. The remaining trace is the output.

4) Using the module

You can use these modules as an universal infrared
receiver for your computer with projects like Lirc.
You build an Infrared Break Beam detector.
You can extend the range of your remote controls by building a repeater.